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Abstract

The ??18O values of gold-bearing quartz from the Juneau gold belt range from 15.2 to 20.8???, indicating that ore fluid values ranged from 7.2 to 12.8??? at an estimated temperature of 300??C. Hydrothermal micas from many of the deposits are characterized by ??D values of -75 to -53???, and ore fluids were calculated to have values of -35 to -15???. In contrast, extracted fluid inclusion waters have a broad range of ??D values, from -48 in relatively undeformed quartz to about -110??? for some of the more deformed quartz veins. This range of more than 60??? reflects various mixtures from inclusions containing isotopically heavy, primary ore fluids and those containing low-temperature, isotopically light meteoric waters that were trapped in late fractures during uplift of the veins to shallow crustal levels. These results indicate a deep crustal source for the ore fluids, most likely of metamorphic origin. The provinciality of ??34S data suggests a regional metamorphic fluid of approximately -6??? that acquired much of its sulfur from lithologies near sites of ore deposition. -from Authors

Additional publication details

Publication type:

Article

Publication Subtype:

Journal Article

Title:

Oxygen, hydrogen, and sulfur isotope studies in the Juneau gold belt, southeastern Alaska: constraints on the origin of hydrothermal fluids